Related Party Transactions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Cash distributions declared and paid	$ 3,100	$ 5,000	$ 3,800
Revenues earned for services provided to related parties	107	104	106
Costs and Expenses, Related Party	405	421	385
Equity Method Investments and Joint Ventures [Abstract]
Investments related to TTX	$ 848	807
TTX Company
Related Party Transaction [Line Items]
Ownership Percentage in TTX Company	17.40%
TTX Company
Related Party Transaction [Line Items]
Costs and Expenses, Related Party	$ 394	409	386
Parent Company
Related Party Transaction [Line Items]
Cash distributions declared and paid	3,100	5,000	3,800
Tax Refunds from Parent Company	65	20	47
Tax payments to parent company	1,200	1,500	$ 1,100
Payable to parent company	$ 170	$ 112